Locking device for push-button stations



March 23, 1954 N. A.IAPPLETON ET AL LOCKING DEVICE FOR PUSH-BUTTONSTATIONS Filed Nov. 14', 1951 Inventors horton aa npleton Richard JKrause Patented Mar. 23, 1954 LOCKING DEVICE FOR PUSH-BUTTON STATIONSNorton A. Appleton and Richard J. Krause, Chicago, 111., assignors toAppleton Electric Company, Chicago, 111., a corporation of IllinoisApplication November 14, 1951, Serial No. 256,258

4 Claims.

'1 The present invention relates in general to the field of locks forelectric switches. More specifically, the invention is concerned with anovel locking device for push-button stations such as locking device ofexceptionally simple and economical construction and which requires nocostly modification in the construction of the switch with which it maybe used but simply takes advantage of switch structure already present.

A further object is to provide a locking device for push-button stationsand which possesses a high degree of flexibility in adaptation and isusable with a wide variety of ordinary padlocks.

Other objects and advantages of the invention will become apparent fromthe following description, taken together with the accompanying drawing,wherein:

Figure 1 is a perspective view of an illustrative push-button stationequipped with a novel locking device which exemplifies the presentinvention.

Fig. 2 is a front elevation of the push-button station and lockingdevice shown in Fig. l, but

with the latter in its locked position.

Fig. 3 is a fragmentary horizontal sectional view of the illustrativedevice taken in the plane of the line 33 in Fig. 2.

Fig. 4 is a fragmentary vertical sectional view through the illustrativedevice, taken in the plane 'of the line 44 in Fig. 2.

Fig. 5 is an enlarged perspective View showing details of the fixedbracket which constitutes a major element of the device.

. Figs. 6 and '7 are elevational views of the movable element of thenovel locking device, illustrating certain variants in its lateral edgecontour.

While the invention is susceptible of various modifications andalternative constructions, certain preferred embodiments have been shownin the drawings and will be described below in considerable detail. Itshould be understood, however, that there is no intention to limit theinvention to thespecific forms of locking devices disclosed herein,but'on the contrary, the intention is to cover allmodifications,alternative constructions and equivalents falling within the spirit andscope of the invention as expressed in the appended claims.

Referring more specifically to the drawings, the invention is thereexemplified in a novel look ing device it installed on an illustrativepushbutton switch II. In this instance, the switch l I happens to be astart-stop switch of the explosion proof type and may, for example, beused to control a remotely located electric motor (not shown). Asillustrated in Fig. 1, the switch ll may be mounted on an appropriatebox l2 and has a plate it which serves as the box cover. A casing l5integral with the plate l4 houses the current carrying elements of theswitch. The casing It has a front face It from which a pair ofresiliently loaded, depressible push-buttons I8, 19 project. The upperbutton, designated by the reference numeral l8, happens to be the startbutton while the lower button, designated by the numeral It, happens tobe the stop button. As indicated in Fig. 4, each push-button is fastenedto an individual plunger 20, the latter being surrounded by a coiledcompression spring 2| interposed between the button and the front faceE6 of the switch casing. Each of the push-buttons It, It is partiallysurrounded by a corresponding one of a pair of protective abutments 22.In this instance, the abutments 22 are of substantially semi-circular orhorseshoe shape and are integral with the switch casing [5. Theabutments 22 are disposed with their open ends facing toward the centerof the face 16, presenting convex surfaces toward the extremities of theface it so as to ward off accidental blows which might otherwise tend todamage the push-buttons l8, IE or bend their plungers 2!).

Taking full advantage of the switch structure thus far described, thenovel locking device [0 comprises a fixed bracket 24 (Figs. 3, 4 and 5)susceptible of rigid attachment to the switch face it in the spacebetween the push buttons l8, l9 and their respective protectiveabutments 22. As shown clearly in Figs. 3 and 5, the mounting bracket 26is substantially U-shaped and comprises a laterally offset intermediateportion 25 terminating in a pair of spaced apart, substantially parallelarms 25, 23. The arm 26 terminates an outturned portion 23 having anoblong lociring eye 38 therein. The arm 2%,on the other hand, terminatesin an outturned portion which may be bifurcated so as to define a pairof closely spaced supporting fingers 3| therein.

The offset portion 25 of the mounting bracket 25 has holes 32 forreceiving mounting screws 36 which may threadedly engage correspondingtapped holes in the switch face I5.

Slidably abutting th outturned portions 29, 3| of the bracket is alocking slide 55 (Figs. 3, 6 and 7). The latter has a locking eyecomparable in size and shape to the eye 35 of the bracket 25. The endportion 38 of the slide 35 remote from the eye 36 is bent toward theswitch face I6 and lies substantially parallel with the bracket arm 28.The slide 35 has an instruck tongue 39 adjacent the eye 36 and bent intosubstantially parallel relation with the arm 25 of the fixed bracket.The members 38, 39 are spanned by a longitudinal sliding pin (Figs. 3and 4) which passes through alined openings 4| in the bracket arms 26,28 so as to hold the slide 35 against the bracket 25.

The slide 35 is normally biased so that its eye 35 will register withthe eye 35 of the mounting bracket, such being accomplished by the useof a coil spring 52 interposed between the arm 28 and the plunger end 35and disposed in surrounding relation with the pin Gil. This position ofthe slide 35 will be designated as its normal position. The slide 35 mayalso be shifted manually to the right, as shown in the drawing, inopposition to the thrust of the biasing spring 42 until the eye 36extends beyond the end of the eye member 29 of the bracket. Thisposition of the slide will be designated as its extended position.

Provision is made in the device to for locking either or both of thepush-buttons l3, iii in a depressed or a non-depressed position,depending upon the requirements of the particular push-button station atwhich the device it] is installed. This is accomplished by contouringeach of the lateral edges of the slide 35 so that it will eitherintercept or remain clear of its associated push-button when the slideis in its normal, as well as in its extended, position. Such contouringmay vary for different applications, being tailored to meet the needsor" a given installation. As shown in Fig. 2, the slide 35 is formedwith a pair of alined clearance notches M, 45, permitting free movementof the respective push-buttons l8, l9 when the slide 35 occupies itsnormal position. When, however, the slide 35 is urged manually into itsextended position as illustrated in Fig. 1, the non-relieved lateraledges thereof are adapted to intercept the push-buttons l8, l3 and toretain either or both of them a depressed or a non-depressed position.Ihe push-buttons may thereupon be locked in a given condition byinserting the l yoke 16 of a padlock through that portion of the eye 35of the slide extending beyond the end of the bracket eye member 29.

tudinally into an intercepting position. On the other hand, coactionbetween the push-buttons and the slide 35 when the push-buttons are innon-depressed position, as illustrated by the push-button IS in Fig. 4,is easily accomplished by contact between the bottom face of eachpushbutton and the slide.

For the purpose of enabling an individual to install the device It) sothat the slide 35 and bracket 25 will be in proper registry with thepush-buttons l8, [9, the eye ends of the memhere 2 1, 35 are laterallyenlarged to define locating shoulders 55, El (Figs. 2 and 5). Theshoulders 55, 5! are proportioned and located so that they will bearagainst the protective abutments 22 on the switch face 16 and preciselyposition the mounting bracket 25 and the slide 35 relative to thepush-buttons.

Preferably, when installing the device H), the bracket 24 alone isinstalled first by means of the mounting screws 34. The slide 35 is thenplaced upon the bracket 25 and the pin and spring 45, 42 are theninstalled in place, such parts being retained in assembled condition asby peening the end of the pin re. With the slide 35 thus mounted inplace, it will be appreciated that the heads of the mounting screws 34are effectively masked, making it extremely diflicult for a carelessoperator to remove the screws 34 and detach the locking device In.

In Figs. 6 and '7, certain variants in edge contour of the slide memberare illustrated. Thus Fig. 6, the upper edge or slide 35A has arelatively long clearance notch 52 which leaves its associatedpush-button free to be operated while the slide 35A is in either itsextended or in its normal position. The bottom edge of the slide 35A hasa smaller clearance notch 54, leaving its associated push-button free tobe operated only when the slide 55A is in its normal position. Theunrelieved lateral edge portion of the slide adjacent the notch 55 isconsequently adapted to engage the push-button and lock it either in itsdepressed or non-depressed position when the slide 35A is in extendedposition. The slide 353, illustrated in Fig. 7, is substantiallyidentical with the slide 35A except for the fact that its longerclearance notch 55 is located on its lower edge while its shorterclearance notch 55 is located on its upper edge. This of course producesa converse locking effect from that produced by the slide 35A.

Upon reflection, it will be appreciated that the locking devicedescribed above adequately fulfills the objects set forth earlierherein. Its two major parts may easily and cheaply be constructed in theform of sheet metal stampings which may be assembled by fasteningelements of utmost simplicity. The device ill in no way complicates orincreases the cost of the push-button switch with which it may be usedbut simply takes advantage of existing switch structure in its mountingarrangement and operation. As indicated earlier herein, the device Illmay, with equal facility, be assembled with the switch at the factory ormay be provided as an attachment to be installed by the user at anexisting push-button station.

We claim as our invention:

1. In a switch structure having a pair of depressible push-buttons, thecombination of an oiTset bracket comprising an intermediate portionsusceptible of rigid attachment to said switch between saidpush-buttons, said bracket also hav ing spaced apart arms one of whichterminates in a locking eye, a locking slide having lateral edgescontoured for selective interception of respective ones of thepush-buttons, said slide also having a locking eye normally disposed inregistry with the locking eye of said bracket, and spring loaded meansinterposed between said bracket and said slide for maintaining thelatter with its locking eye normally in registry with the locking eye ofsaid bracket.

2. In a switch structure having a pair of depressible push-buttons andalso having a pair of protective abutments disposed in spaced apartopposed relation adjacent respective ones of said push-buttons, thecombination comprising a bracket having an oifset intermediate portionsusceptible of rigid attachment to said switch between said push-buttonsand said abutments, said bracket also having spaced apart arms, alocatin shoulder on one of said arms adapted for abutting engagementwith one of said protective abutments, said one arm also terminating inan outturned locking eye, a locking slide having a normal position andan extended position, said slide also having lateral edges selectivelycontoured for interception of respective ones of the push-buttons withsaid slide in either position, said slide having a locking eye, alocating shoulder on said slide adapted for abutting engagement with oneof said protective abutments, a pin fixed to said slide and to saidbracket but having sliding engagement with the latter, and a loadingspring interposed between said bracket and said slide for maintainingthe latter with its locking eye normally in registry with the lockingeye of said bracket, said loading spring being disposed in surroundingrelation with said pin.

3. An external locking device for push-button stations comprising, incombination, an ofiset bracket having a medial portion adapted for fixedattachment to a pair of depressible push-buttons, said bracket alsohaving spaced apart arms one of which terminates in a locking eye, alocking slide having lateral edges selectively contoured forinterception of respective ones of the pushbuttons in a depressed aswell as in a nondepressed position, said slide also having a looking eyenormally disposed in registry with the 6 locking eye of said bracket,and spring loaded means interposed between said bracket and said slidefor maintaining the latter with its locking eye normally in registrywith the locking eye of said bracket.

4. An external locking device for a switch structure having a pair ofdepressible push-buttons and a pair of protective abutments disposed inspaced apart opposed relation adjacent respective ones of saidpush-buttons, said locking device comprising, in combination, a brackethaving an ofiset intermediate portion susceptible of rigid attachment tosaid switch between said pushbuttons and said abutments, said bracketalso having spaced apart arms, a locating shoulder on one of said armsadapted for abutting engagement with one of said protective abutments,said one arm also terminating in an outturned locking eye, a lockingslide having a normal position and an extended position, said slide alsohaving lateral edges selectively contoured for interception ofrespective ones of the push-buttons with said slide in either position,said slide having a looking eye, a locating shoulder on said slideadapted for abutting engagement with one of said protective abutments, apin fixed to said slide and to said bracket but having slidingengagement with the latter, and a loading spring interposed between saidbracket and said slide for maintaining the latter with its locking eyenormally in registry with the locking eye of said bracket.

NORTON A. APPLETON. RICHARD J. KRAUSE.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,205,798 Scholder Nov. 21, 1916 2,579,168 Ballou Dec. 18,1951

